A Many-Body Theory of the Optical Conductivity of Excitons and Trions in Two-Dimensional Materials
| Autor: | Christina Manolatou, Okan Koksal, Farhan Rana |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
Exciton
Many-body theory FOS: Physical sciences 02 engineering and technology Polaron 01 natural sciences Optical conductivity Condensed Matter::Materials Science Condensed Matter - Strongly Correlated Electrons Mesoscale and Nanoscale Physics (cond-mat.mes-hall) 0103 physical sciences Bound state 010306 general physics Physics Condensed Matter::Quantum Gases Condensed Matter - Materials Science Strongly Correlated Electrons (cond-mat.str-el) Condensed matter physics Condensed Matter - Mesoscale and Nanoscale Physics Condensed Matter::Other Materials Science (cond-mat.mtrl-sci) 021001 nanoscience & nanotechnology Condensed Matter::Mesoscopic Systems and Quantum Hall Effect Excited state Condensed Matter::Strongly Correlated Electrons Sum rule in quantum mechanics Trion 0210 nano-technology |
| Popis: | The optical spectra of two dimensional (2D) materials exhibit sharp absorption peaks that are commonly identified with exciton and trions (or charged excitons). In this paper, we show that excitons and trions in doped 2D materials can be described by two coupled Schrodinger-like equations - one two-body equation for excitons and another four-body equation for trions. In electron doped 2D materials, a bound trion state is identified with a four-body bound state of an exciton and an excited conduction band electron-hole pair. In doped 2D materials, the exciton and the trions states are the not the eigenstates of the full Hamiltonian and their respective Schrodinger equations are coupled due to Coulomb interactions. The strength of this coupling increases with the doping density. Solutions of these two coupled equations can quantitatively explain all the prominent features experimentally observed in the optical absorption spectra of 2D materials including the observation of two prominent absorption peaks and the variation of their energy splittings and spectral shapes and strengths with the electron density. The optical conductivity obtained in our work satisfies the optical conductivity sum rule exactly. A superposition of exciton and trion states can be used to construct a solution of the two coupled Schrodinger equations and this solution resembles the variational exciton-polaron state, thereby establishing the relationship between our approach and Fermi polaron physics. 13 pages, 9 Figures, few typos corrected from the previous version and few more references added |
| Databáze: | OpenAIRE |
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